STROBILIZATION OF AURELIA 87 



neck connecting one ephyra with its neighboifr is now reduced 

 to the four longitudinal muscle-strands, each surrounded by a 

 strip of endoderm, while the wall of the neck has become con- 

 verted into the manubrium and spread out horizontally. 



Heric (4), working on Chrysaora, shows the intersegmental 

 folds, but states that they occur only between the septa as 

 four bladder-like outgrowths of both layers. These, on breaking 

 away distally from the exumbrella of the upper ephyra, 

 spread outwards as four semicircular flaps the adjacent edges 

 of which meet and fuse in the interradii, so producing the 

 flat manubrium. Thus, he says, the connecting strands have 

 endoderm on the inner side and ectoderm on the outside 

 (whereas in Aurelia, according to Glaus as we have just seen, 

 ectoderm is entirely absent). 



Glaus and Heric show, then, that the manubrium is under- 

 going development at the same time as the rest of the ephyra, 

 and that the lining of the manubrium is of endoderm. 



Glaus also states that the manubrium of the polyp, which 

 remains after strobilization, is lined by endoderm, so that at 

 no time is there a stomodaeum such as is described by Goette. 

 The work of Friedemann (3) and Hein (2) on the embryological 

 aspect confirms the above as regards the endodermal lining 

 of the manubrium and the absence of stomodaeum. 



Glaus and Heric state that the gastral filament is derived 

 by the transformation of the columella, i. e. the axial portion 

 (internal to the ostium) of the taeniole containing the longi- 

 tudinal muscle-strand, which for a time connects the sub- 

 umbrella and exumbrella of a developing ephyra. 



With regard to the septal muscle-strands Goette has described 

 them as hollow structures with the cavity continuous with 

 that of the peristomial pit. Glaus (1), Friedemann (3), and 

 Heric (4) state that the muscles are solid structures, and 

 Friedemann figures the peristomial pit of a well-developed 

 scyphistoma as being distinct from the septal muscle. 



There does not appear to be any record of an observation 

 on the development of the peristomial pits in a non-terminal 

 ephyra. Glaus (loc. cit.), in one figure, indicates a peristomial 



